Non-polymeric open-chain sensitizers



United States Patent 3,038,805 NON-POLYMERIC OPEN-CHAHN SENSITIZERS John R. Darin, Peter P. Chiesa, and William G. Lovett,

Rochester, N.Y., assignors to Eastman Kodak Company, Rochester, N.Y., a corporation of New Jersey No Drawing. Filed Oct. 14, 1959, Ser. No. 346,230 21 Claims. (Cl. 96-100) This invention relates to photographic silver halide emulsions, and more particularly, to an improved means for sensitizing such photographic silver halide emulsions.

A number of methods have been previously described for increasing the sensitivity of photographic silver halide emulsions, other than methods of optical or spectral sensitization, which involve the incorporation of certain colored compounds or dyes in the emulsions. The incorporation of such dyes in the emulsions increases the optical range of sensitivity, and for this reason such dyes are commonly referred to as optical or spectral sensitizing dyes. It is also well known to increase the sensitivity of photographic emulsions by addition of sulfur compounds capable of reacting with silver salts to form silver sulfide, or with reducing agents (compounds of these types are also naturally present in gelatin), or with salts of gold or other noble metals, or with combinations of two or more of the aforementioned compounds generally known as chemical sensitizers. Such chemical sensitizers are believed to react with the silver halide to form, on the surface of the silver halide, minute amounts of silver sulfide or of silver or of other noble metals, and these processes are capable of increasing the sensitivity of developing-out emulsions by very large factors. The process of chemical sensitization, however, reaches a definite limit beyond which further addition of sensitizer, or of further digestion with the sensitizer present, merely increases the fog of the photographic emulsion with constant or decreasing speed.

We have now found a means of further increasing the sensitivity of photographic emulsions which may be applied even though the ordinary processes of chemical sensitization have been carried to the effective limit of the photographic emulsion in question. Our process is to be distinguished from hypersensitization, which is produced by bathing a finished coating with water or with solutions of ammonia, amines or silver salts. Such processes act primarily on optically sensitized photographic emulsions and tend to increase the free silver ion con centration of the emulsion and greatly diminish its stability. Our process is also to be distinguished from hypersensitization by mercury vapor, which gives a transitory efiect which is lost on storage of the film. The compounds used in our invention do not appear to be chemical sensitizers in the usual sense, since they increase speed by their presence during exposure and processing and require no digestion with the photographic emulsion to produce an increase in speed, nor does their chemistry indicate that they are likely to react with silver halide under normal emulsion conditions.

The novel sensitizers of our invention are quite unique in that the effects produced are additive in photographic emulsions which have already been sensitized to their optimum, or near-optimum, with conventional chemical sensitizers, such as labile sulfur compounds. The novel sensitizers of our invention, however, can be used to sensitize photographic silver halide emulsions containing no other sensitizers, if desired. The novel sensitizers of our invention are not strictly chemical sensitizers, since chemical sensitizers do not generally provide the additive effects of the type mentioned.

It is, therefore, an object of our invention to provide photographic silver halide emulsions which have been sensitized with various non-polymeric compounds com ice taining a plurality of sulfur atoms. Another object of our invention is to increase the sensitivity of ordinary photographic silver halide emulsions which have been sensitized with chemical sensitizers, such as compounds containing labile sulfur atoms, or gold-containing compounds. Other objects will become apparent from a consideration of the following description and examples.

According to our invention, we have found that the sensitivity of an ordinary photographic silver halide emulsion can be materially increased by incorporating therein non-polymeric open-chain compounds, which can be characterized as polyoxathio others. These non-polymeric compounds contain their sulfur atoms in the form of thioether linkages. By thioether linkages, we mean a linkage wherein the sulfur atom is divalent and is joined to two non-oxocarbonylic carbon atoms. Compounds useful in sensitizing photographic silver halide emulsions according to the present invention are to be distinguished from the polymeric thioether compounds described in US. patent application Serial No. 779,874, filed December 12, 1958, by J. R. Dann and I. J. Chechak. The polymeric compounds described in this latter application are generally characterized as having high molecular weights and as containing characteristic repeating units or groups.

The sensitizing compounds useful in practicing our invention are non-polymeric and can be represented by the following general formula:

wherein X represents a divalent linkage selected from oxygen, sulfur, and the group:

--X CH CH X wherein X and X each represents an oxygen atom or a sulfur atom, provided at least one of the groups se lected from X, X and X is an oxygen atom and at least one of the groups selected from X, X and X is a sulfur atom, X represents a methylene carboxy radical, i.e.,

o It CH2CO R represents a hydroxyl group, an alkoxyl group (e.g., methoxyl, et-hoxyl, propoxyl, butoxyl, etc.), a car-bamyl group, i.e.,

O NHJA- or a carboxylic acyloxyl group, such as acetoxyl, butyroxyl, etc., R represents an ethylene radical, such as ethylene or ethylene substituted by an alkyl group, such as methyl, d represents a positive integer of from 1 to 2 and n represents a positive integer of from 1 to 3.

The compounds of Formula I above can be prepared according to methods which have been previously described in the technical literature. For example, these compounds can be prepared by condensing together a monothiol with a dihalogenated ether compound in the presence of sufficient alkali to form the alkali metal salt of the monothiol. Alternatively, these compounds can be prepared by condensing together an organic halide with sodium sulfide. These two alternative methods of .syntheses can be outlined as follows:

METHOD A The reaction of a mercaptan with a dihalide "17.3. Found: c, 52.0; H, 9.2; s, 17.6.

described in Example below, using sodium sulfide nonaa METHOD B A mixture of 2.3 g. (0.1 mole) of sodium, 9.1 g. (0.05 Th ti mole) of 1,2-bis(2-mercaptoethoxy)ethane and 13.9 g.

e a bah e wdmm sulfida (0.1 mole) of methoxyethyl bromide in 100 ml. of ab- 2 solute ethanol was refluxed on a steam bath for 2% hours, after which the solvent was stripped otf with a water aspirator, and the residue was extracted with three 50-1111. portions of hot ethyl acetate. The extracts were dried over anhydrous sodium sulfate, the solvent was removed and the residue distilled in vacuum to give the product boiling at 174 C./1 mm.

Analysis.-Calcd. for C I-1 0 8 C, 48.3; H, 8.7; S, 21.5. Found: C, 48.4; H, 8.7; S, 21.4.

0 0 Example 5 .Preparation 0 3,6,9,15,18,21-Hex0xa-I2- H Thiatricosane NH2( 3CHCHzSR-SOH2GHGNH2 H (l /H 3 CH CH OCH CH OCH CH OCH CH SCH In the above exemplary reactlons, R defines the non- CH OCHzCHzOCHzCH OCH2cH3+2NaBr reactive portions of the molecule and does not have the 2 2 A solution of 9 g. (0.0375 mole) of sodium sulfide definitions assigned above for this group.

These methods of syntheses are illustrated in the folnonahydl'ate Of Water, a ((1075 mole) lowing examples; of ethogyetloxyeitlhoxyethyl bromide in 10 [1111. ethanol was re uxe w1t a water asplrator, t1 c on mess ap- Example lrprepamnw 9 1J4'Dlhydroxy'69'Dmxa' peared, after which the mixture was extracted with ethyl 312'Dlthatetradwme acetate. Drying the extract over anhydrous sodium sul- NSBCOQ 25 fate, followed by removal of the ethyl acetate and dis- ZHOCHzCmSH clcHoHzo CHCHOOHCHZOI tillation in vacuum gave a product boiling at 172 C./1

I HOCHgCH2SCH2CHzOCH2CH2OCI-IzCHzSCHzCH2OH mm 2-mercaptoethanol, 15.6 g. (0.2 mole), and 1,2-bis(2- Analysis-Calm. for C H O S: C, 54.3; H, 9.6; S, chloroethoxy)ethane, 18.7 g. (0.1 mole) were dissolved 9.0; mol. wt., 354. Found: C, 53.8; H, 9.7; S, 9.1; mol. in 50 ml. of ethanol and mixed with 50 ml. of water wt, 336. containing 0.1 mole of sodium carbonate. The reaction mixture was heated under a reflux condenser on the steam bath for 20 hours, the solvent removed under vacuum, and the product separated from the sodium chloride formed, by extraction with hot absolute ethanol 3 and ethyl acetate. The solvents were removed from the combined extracts and the product was distilled. B.P. 220230 C./3 mm.

Analysis.-Calcd. for C H S O C, 44.4; H, 8. s, 23.7; mol. Wt., 270. Found: c, 44.5; H, 8.0; s, 23. mol. wt., 277.

The compounds of Formula I above, wherein R rep- 5 resents a carbamyl group, can be prepared according to the following method:

METHOD C Example 6 .Preparation of 3,9,12,18-Tetr0xa-6J5- Dithiaeicosane 2611 01120 CHQCHQBI I-ISCHgCH OOHzCHzOomomsrr 011 013 0OH GII SCII CILOGH CH OOH CH SCH CH OCH CH Following the procedure of Example 1 above, using 5.3 1; g. (0.05 mole) of sodium carbonate, 9.1 g. (0.05 mole) 3 49 of 1,2 bis(Z-mercaptoethoxy)ethane, and 15.3 g. (0.1 mole) of ethoxyethyl bromide in SO-percent ethanol, a product was obtained which boiled at l72174 C./1 /z Example 2.Preparati0n of 3,6,12,18,21-Pent0xa-9J5- mm.

Dithiatricosane Analysis.-Calcd. for C H O S C, 51.5; H, 9.2; S,

CHgOHzO CHgCHzO CH CH SCHzCHflO OHzCHaSCHgCHzO CHzCHzO CHgCHa A mixture of 5.3 g. (0.05 mole) of sodium carbonate, 50 19.7; mol. wt., 326. Found: C, 51.0; H, 9.0; S, 19.6; 6.9 g. (0.05 mole) of bis mercaptoethyl ether, and 19.7 mol. wt., 335. g. (0.1 mole) of ethoxyethoxyethyl bromide in 60 ml. of 50 percent ethanol was refluxed on a steam bath over- Example W g y; 3 23 T'mxa Dnhla night. Most of the ethanol was stripped 011 with a water NaZCOQ aspirator, the residual matenal was extracted with ethyl mmomocmcmm HSCHZOHaO C-HBCHzSH acetate, and the extracts were dried over anhydrous sodium sulfate. Removal of the ethyl acetate and distillation in vacuum gave the product boiling at 2l4-218 C./1 mm.

Analysis.Calcd. fOI' C16H34O5S2I C, H, S,

CHQCHZOCHQCHZSOH2CH2OOHZCHZSCH2C ZOCHZG Z Following the procedure of Example 1 above, using 2.65 g. (0.025 mole) of sodium carbonate, 3.45 g. (0.025 mole) of bis mercaptoethyl ether and 7.65 g. (0.05 mole) of ethoxyethyl bromide in S D-percent ethanol, 2. product was obtained which boiled at 147 C./ 2 mm.

Analysis.--Calcd. for C H gO S C, 51.0; H, 9.2; S, 22.7. Found: C, 50.3; H, 8.9; S, 23.5.

Exrmiple 8 .3 ,6,] 5 ,1 8-Tetr0xa-9,1 Z-Dithiaeicosane NazCOa 2CH OH OCH2OH20CH2OH2Br HSCHZQHQSH OH GH OCH OHzOOH OH SOHQCH2SOH CH OCH OHQOCHgCH; Following the procedure of Example 1 above, using 5.3 g. (0.05 mole) of sodium carbonate, 4.7 g. (0.05

mole) of ethane dithiol, and 19.7 g. (0.1 mole) of ethoxyethoxyethyl bromide in SO-percent ethanol, a product Na was obtained which boiled at l72-173 C./2 /2 mm. ZCHSOCHMHQBY HSCHQCHwCHZCHWCHQCHZSH Analysis.Calcd. for 0 111 05,; 0, 51.5; H, 9.2; s,

OH3OCHZCHZSCH2OH2OOH2CHZOCH2GH2SCH2CH20CH3 75 19 7 Found; C, 51.1; H, 89; S, 19 4 I Example 3.Preparation 0f 3,6,12,15-Tetra0xa-10- Thiaheptadecane 2C2H5OCH2CH2OCH2CH BT+Nags C H OCH CH OCH CH SCH CH OCH CH OC H 5 This compound was prepared according to the method hydrate dissolved in water and ethoxyethoxyethylbromide. in ethanol.

Example 4.-Preparati0n of 2,8,11,17-Tetr0xa-5,14- Dithz'aoctadecane 5 Example 9.Preparation of 1,17-Dihydrxy-3,9,15-Triappearance, was boiled in ethyl acetate with decolorizing wee-6,12-Dithiaheptadecane-4,14-Dione carbon, filtered, dried, and the solvent evaporated in vac- M2003 uum on a steam bath, leaving an amber oil. HSCHZCI'IQOCHZOHZSH 2BICH2000CH2CH2OH Analysis.-Calcd. for 0 1-1 0 C, 46.4; H, 7.2; S,

nooniornoooornsonlontoomonisonioooongonzorr 5 15.4. Found: C, 46.2; H, 7.4; S, 15.7.

A mixture 255 mole) 0f Sodium carbon Example J4.-Preparation 0f 2,5,11,17,20-Pent0xa-8,14- ate, 3.45 g. (0.025 mole) of his mercaptoethyl ether, and Difhighgneicosane-fi, 16 Di ne 9.15 g. (0.05 mole) of hydroxyethyl bromoacetate in 50 0 ml. of 50-percent ethanol was refluxed on a steam bath overnight. Most of the ethanol was distilled off and the 0 HSCHQCHZOCECHQSH ZOHtQCHQOHtOOCHZBT cloudy residual mixture was extracted with three 50-1111. 0 0 Portions of Ethyl acetate After drying the eXtIaCiS Over orno oi-rzcnzor iornsornornoorrzougsonzdoonicrnoon, anhydrous sodium sulfate, removal of the ethyl acetate A mixture of 5.3 g. (0.05 mole) of sodium carbonate, g at room temperature left the Product as a hght 6.9 g. (0.05 mole) of his mercaptoethyl ether, and 19.7 g.

. (0.1 mole) of methoxyethyl bromoacetate in 100 ml. of i ggifgg fi 50-percent ethanol was refluxed on a steam bath for 6 hours, after which most of the ethanol was distilled off. Example 10.Preparati0n of Z,2,3-Dihy r y-3, J2, Upon cooling, a heavy oil separated, which was drawn ofi. 18,21-Pent0xa-9,15-Dithiatricosane-7J7-Di0ne The aqueous residue was extracted with three portions of NEMCOS HSCHQOHZOCI'IQCHQSH 2BICH2COOCH2CH2O OHQGHQOH HOCHgCHrOCHzCH2OOCCH2SCH2CH2OOHgCHzSCHzCOOCH CH OCH CH OH Following the procedure of Example 9, using 2.65 gethyl acetate totaling 200 ml, and the combined oil and [11016) of Sodium Carbonate, gof ibis extracts were dried over anhydrous sodium sulfate. Recapwethyl ether, and 11-35 111013) Y Y- moval of the solvent, followed by distillation in vacuum ethoxyethyl bromoacetate, the product was obtained as 3 gave thg product b ili at 297 210 C at 2 mm y py Oil. Analysis.Calcd. for c n o s z c, 45.4; H, 7.0; s,

Example 11.-Preparation of 1,20-Dihydr0xy-3,9,l2, Found: 1

18-Tetr0xa-6,15-Dithiaeicosane-4J7-Di0ne In a manner similar to that illustrated above, other non- HO OH2CH2O o 0 01128011201110 011201120 omomsoino o 0 CHZCIIQOH Following the procedure of Example 9 above, using polymeric sensitizers embraced by Formula I can be pre- 15.6 g. (0.147 mole) of sodium carbonate, 26.75 g. pared. The compounds of Formula I above, where R (0.147 mole) of 1,2 bis(Z-rnercaptoethoxy)ethane, and represents an acyloxyl group, can be prepared by reacting 55 g. (0.3 mole) of hydroxyethyl *bromoacetate, the prodthe compounds of Formula 1 above, where R represents a uct was obtained as a syrupy oil. hydroxyl group, with a carboxylic halide or car-boxylic Analysis.-'Calcd. for C H O S C, 43.5; H, 6.7; S, 40 anhydride. The desired compound spontaneously forms. 16.7; mol. wt., 386. Found: C, 42.8; H, 6.9; S, 16.8; The sensitizing compounds of our invention can be mol. wt., 397. added to ordinary photographic silver halide emulsions Example 12' 7,10 Diwali1&Dithiahexadecanek2,15 for the purpose of increasing the sensitivity thereof, as

has been indicated above.

plcmbofcamlde l The preparation of photographic silver halide emulsions Reaction of methacrylamlde and 'blsa'mercaptoeh involves three separate operations: (1) emulsification and oxykthane digestion of silver halide, (2) the freeing of the emul- IIJHQ sions of excess water-soluble salts, usually by washing 2on2=oooNrn rrsoInoi-noonioi-noonioinsrr with water, and (3) the second digestion of after-ripen- CH3 CH3 ing to obtain increased emulsion speed or sensitivity (Mees, The Theory of the Photographic Process, 1954).

NHzGOCHCHQSCHQCHZOCHzCHzOCHeCHzSGHzCIICONHs The sensitize of our invention can be added to the Seventeen grams of methacrylamide (0.2 mole), 1 emulsion before the final digestion or after-ripening, or g. of bis(2-mercaptoetl1oxy)ethane (0.1 mole), and they can be added immediately prior to the coating. Our drops of benzyl trimetnylammonium hydroxide solution new phstographic sfinsitizers require no Special final diges were dissolved in 250 ml. of ethanol. After 11 hours of tion or aftepripfining refluxing, the solvent was evaporated and the solid re The panicular quantity of Sensitizer used in a givan maining was recrystallised from ethyl acetate. Fourteen emulsion can Vary depending upon the effects desired grams material meltmg at 71-740 0 Were o'btalmd' degree of ripening, silver content of the emulsion, etc. Anazysls-*calcdfor C14H23N2S2O4: 47-8; The amount used is also dependent upon the particular 182; Found: 472; H 51 NA; 69 stage at which the sensitizer was added during the prep- Example 13.-Preparation of 2,5,11,14,20,23-Hex0xa' aration of the emulsion. We have found that generally 8,17-Dithiatetrac0sane-6,. 9-Dione from about 50 mg. to about 5 g. or" sensitizer per mole of H HSCHQCHQOGH2CH2OOH2CHZSH 201130 CHQCHZOCCIIZBI i ii CHKO zCHaOCCHzSCHzCHsOOHzCHzOCHsCHgSCI-BCOCHQCHQOCHg Following the procedure of Example 12, using 6.2 g. silver halide are quite adequate to accomplish the desired (0.05 mole) of sodium carbonate monohydrate, 9.1 g. 70 sensitization. (0.05 mole) of 1,2-bis(2-rnercaptoethoxy)ethane, and The sensitizers of our invention can be added to photo- 19.7 g. (0.1 mole) of methoxyethyl bromoacetate, a prodgraphic emulsions using any of the well known techniques uct was obtained which boiled over the range of 166-188 in emulsion making. For example, the sensitizers can be C. at 2 mm. Decomposition began when further distildissolved in a suitable solvent and added to the silver lation was attempted. The product, somewhat dark in halide emulsion, or they can be added to the emulsion in the formof a dispersion similar to the technique used to incorporate certain types of color-forming compounds (couplers) in a photographic emulsion. Techniques of this type are described in Jelley et al. U.S. Patent 2,322,- 027, issued June 15, 1943, and Fierke et al. U.S. Patent 2,801,171, issued July 30, 1957. As indicated above, the solvent should be selected so that it has no harmful efiect upon the emulsion, and generally solvents or diluents which are miscible with water are to be preferred. Water or dilute alkali is a dispersing medium for some of the sensitizers of the invention. In a preferred embodiment, the sensitizers can be dissolved in a solvent, such as etha nol, acetone, pyridine, N,N-dimethylformamide, etc., and added to the emulsion in this form. If desired, certain of the sensitizers can be prepared in finely-divided form and dispersed in water alone, or in the presence of a suitable dispersing agent (such as alkali metal salts of aromatic or aliphatic sulfonic acids) and added to the emulsion in this form. It is quite apparent that the sensitizers of our invention should have suificient water-dispersibility so that they can be adsorbed to or associated with the grains of the silver halide present in the emulsion in sufiicient amount to sensitize the emulsion. It is apparent that the optimum amount for each of the sensitizers will vary somewhat from emulsion to emulsion and from compound to compound. The optimum amount of any given sensitizer can be determined for any particular emulsion by running a series of tests in which the quantity of sensitizer is varied over a given range. Exposure of the treated emulsion in conventional photographic testing apparatus, such as an intensity scale sensitometer, will reveal the most advantageous concentrations for that sensitizer in that particular emulsion. Such matters are well understood by those skilled in the art.

The photographic emulsions used in practicing our invention are of the developing-out type.

The emulsions can be chemically sensitized by any of the accepted procedures. The emulsions can be digested with naturally active gelatin, or sulfur compounds can be added such as those described in Sheppard US. Patent 1,574,944, issued March 2, 1926, Sheppard et a1. U.S. Patent 1,623,499, issued April 5, 1927, and Sheppard et a1. U.S. Patent 2,410,689, issued November 5, 1946.

The emulsions can also be treated with salts of the noble metals such as ruthenium, rhodium, palladium, iridium, and platinum. Representative compounds are ammonium chloropalladate, potassium ohloroplatinate,

and sodium chloropalladite, which are used for sensitizing in amounts below that which produces any substantial fog inhibition, as described in Smith and Trivelli U.S. Patent 2,448,060, issued August 31, 1948, and as antifoggants in higher amounts, as described in Trivelli and Smith U.S. Patents 2,566,245, issued August 28, 1951, and 2,566,263, issued August 28, 1951.

The emulsions can also be chemically sensitized with gold salts as described in Waller et al. U.S. Patent 2,399,- 083, issued April 23, 1946, or stabilized with gold salts as described in Damschroder U.S. Patent 2,597,856, issued May 27, 1952, and Yutzy and Leermakers U.S. Patent 2,597,915, issued May 27, 1952. Suitable compounds are potassium ohloroaurite, potassium 'aurithiocyanate, potassium chloroaurate, auric trichloride and Z-aurosulfobenzothiazole methochloride.

The emulsions can also be chemically sensitized with reducing agents such as stannous salts (Carroll U.S. Patent 2,487,850, issued November 15, 1949), polyamines, such as diethyl triamine (Lowe and Jones U.S. Patent 2,518,698, issued August 15, 1950), polyamines, such as spermine (Lowe and Allen U.S. Patent 2,521,925, issued September 12, 1950), or bis(fl-aminoethyl) sulfide and its water-soluble salts (Lowe and Jones U.S. Patent 2,521,926, issued September 12, 1950).

The emulsions can also be optically sensitized with cyanine and merocyanine dyes, such as those described in Brooker U.S. Patents 1,846,301, issued February 23,

1932; 1,846,302, issued February 23, 1932; and 1,942,854, issued January 9, 1934; White U.S. Patent 1,990,507, issued February 12, 1935; Brooker and White U.S. Patents 2,112,140, issued March 22, 1938; 2,165,338, issued July 11, 1939; 2,493,747, issued January 10, 1950, and 2,739,964, issued March 27, 1956; Brooker and Keyes U.S. Patent 2,493,748, issued January 10, 1950; Sprague U.S. Patents 2,503,776, issued April 11, 1950, and 2,519,001, issued August 15, 1950; Hesteltine and Brooker U.S. Patent 2,666,761, issued January 19, 1954; Hesteltine U.S. Patent 2,734,900, issued February 14, 1956; Van Lare U.S. Patent 2,739,149, issued March 20, 1956; and Kodak Limited British Patent 450,958, accepted July 15, 1936.

The emulsions can also be stabilized with the mercury compounds of Allen, Byers and Murray U.S. Patent 2,728,663, issued December 27, 1955 Carroll and Murray U.S. Patent 2,728,664, issued December 27, 1955; and Leubner and Murray U.S. Patent 2,728,665, issued December 27, 1955; the triazoles of Heimbach and Kelly U.S. Patent 2,444,608, issued July 6, 1948; the azaindenes of Heimbach and Kelly U.S. Patents 2,444,605 and 2,444,606, issued July 6, 1948; Heimbach U.S. Patents 2,444,607, issued July 6, 1948, and 2,450,397, issued September 28, 1948; Heimbach and Clark U.S. Patent 2,444,609, issued July 6, 1948; Allen and Reynolds U.S. Patents 2,713,541, issued July 19, 1955, and 2,743,181, issued April 24, 1956; Carroll and Beach U.S. Patent 2,716,062, issued August 23, 1955; Allen and Beilfuss US. Patent 2,735,769, issued February 21, 6; Reynolds and Sagal U.S. Patent 2,756,147, issued July 24, 1956; Allen and Sagqrra U.S. Patent 2,772,164, issued November 27, 1956, and those disclosed by Birr in Z. wiss. Phot., vol. 47, 1952, pages 228; the disulfides of Kodak Belgian Patent 569,317, issued July 31, 1958; the quaternary benzothiazolium compounds of Brooker and Staud U.S. Patent 2,131,038, issued September 27, 1938, or the polymethylene bisbenzothiazolium salts of Allen and Wilson U.S. Patent 2,694,716, issued November 16, 1954 (e.g., decamethylene-bis-benzothiazolium perchlorate); or the zinc and cadmium salts of Jones U.S. Patent 2,839,405, issued June 17, 1958; and the carboxymethylmercapto compounds of Murray, Reynolds and Van Allan U.S. Patent 2,819,965, issued January 14, 1958.

The emulsions may also contain speed increasing compounds of the quaternary ammonium type of Carroll U.S. Patent 2,271,623, issued February 3, 1942; Carroll and Allen U.S. Patent 2,288,226, issued June 30, 1942; and Carroll and Spence U.S. Patent 2,334,864, issued November 23, 1943; and the polyethylene glycol type of Carroll and Beach U.S. Patent 2,708,162, issued May 10, 1955 or the thiopolymers of Graham and Sagal U.S. application Serial No. 779,839, filed December 12, 1958, or Dann and Chechak U.S. application Serial No. 779,874, filed December 12, 1958, or the quaternary ammonium salts and polyethylene glycols of Piper U.S. Patent 2,886,437, issued May 12, 1959.

The emulsions may contain a suitable gelatin plasticizer such as glycerine; a dihydroxy alkane such as 1,5-pentane diol as described in Milton and Murray U.S. application Serial No. 588,951, filed June 4, 1956; an ester of an ethylene bis-glycoiic acid such as ethylene bis(methyl glycolate) as described in Milton U.S. application Serial No. 662,564, filed May 31, 1957; bis-(ethoxy diethylene glycol) succinate as described in Gray U.S. application Serial No. 604,333, filed August 16, 1956, or a polymeric hydrosol as results from the emulsion polymerization of a mixture of an amide of an acid of the acrylic acid series, an acrylic acid ester and a styrene-type compound as described in Tong U.S. Patent 2,852,386, issued September 16, 1958. The plasticizer may be added to the emulsion before or after the addition of a sensitizing dye, if used.

The emulsions may be hardened with any suitable hardener for gelatin such as formaldehyde; a halogensubstituted aliphatic acid such as mucobromic acid as described in White U.S. Patent 2,080,019, issued May 11, 1937; a compound having a plurality of acid anhydride groups such as 7,8-diphenylbicyclo (2,2,2)-7-octene-2,3, 5,6-tetra-carboxylic dianhydride, or a dicarboxylic or a disulfonic acid chloride such as terephthaloyl chloride or naphthalene-1,S-disulfonyl ChlOl'ide as described in Allen and Carroll U.S. Patents 2,725,294 and 2,725,295, both issued November 29, 1955; a cyclic 1,2-diketone such as cyclopentane-1,2-dione as described in Allen and Byers U.S. Patent 2,725,305, issued November 29, 1955; a bisester of methane-sulfonic acid such as 1,2-di-(methane-sulfonoxy)-ethane as described in Allen and Laakso U.S. Patent 2,726,162, issued December 6, 1955; 1,3-dihydroxymethylbenzimidazol-Z-one as described in July, Knott and Pollak U.S. Patent 2,732,316, issued January 24, 1956; a dialdehyde or a sodium bisulfite derivative thereof, the aldehyde groups of which are separated by 2-3 carbon atoms, such as B-methyl glutaraldehyde bissodium bisulfite as described in Allen and Burness U.S. patent application Serial No. 556,031, filed December 29, 1955; a bis-aziridine carboxamide such as trimethylene bis(1-aziridine carboxamide) as described in Allen and Webster U.S. patent application Serial No. 599,891, filed July 25, 1956; or 2,3-dihydroxy dioxane as described in Jefifreys U.S. Patent 2,870,013, issued January 20, 1959.

The emulsions may contain a coating aid such as saponin; a lauryl or oleyl monoether of polyethylene glycol as described in Knox and Davis U.S. Patent 2,831,- 766, issued April 22, 1958; a salt of a sulfated and alkylated polyethylene glycol ether as described in Knox and Davis US. Patent 2,719,087, issued September 27, 1955 an acylated alkyl taurine such as the sodium salt of N- oleoyl-N-rnethyl taurine as described in Knox, Twardokus and Davis U.S. Patent 2,739,891, issued March 27, 1956; the reaction product of a dianhydride of tetracarboxybutane with an alcohol or an aliphatic amine containing from 8 to 18 carbon atoms which is treated with a base, for example, the sodium salt of the monoester of tetracarboxybutane as described in Knox, Stenberg and Wilson U.S. Patent 2,843,487, issued July 15, 1958; a watersoluble maleopimarate or a mixture of a water-soluble maleopimarate and a substituted glutamate salt as described in Knox and Fowler U.S. Patent 2,823,123, issued February 11, 1958; an alkali metal salt of a substituted amino acid such as disodium N-(carbo-p-tert. octylphenoxypentaethoxy)-glutamate as described in Knox and Wilson U.S. patent application Serial No. 600,679, filed July 30, 1956; or a sulfosuccinamate such as tetrasodium N-(1,2-dicarboxyethyl)-N-octadecyl sulfosuccmamate or N-lauryl disodium sulfosuccinamate as described in Knox and Stenberg U.S. patent application Serial No. 691,125, filed October 21, 1957.

The addenda which we have described may be used in various kinds of photographic emulsions. In addition to being useful in X-ray and other nonoptically sensitized emulsions they may also be used in orthochromatic, panchromatic, and infrared sensitive emulsions. They may be added to the emulsion before or after any sensitizing dyes which are used. Various silver salts may be used as the sensitive salt such as silver bromide, silver iodide, silver chloride, or mixed silver halides such as silver chlorobromide or silver bromoiodide. The agents may be used in emulsions intended for color photography, for example, emulsions containing color-forming couplers or emulsions to be developed by solutions containing couplers or other color-generating materials, emulsions of the mixed-packet type, such as described in Godowsky U.S. Patent 2,698,794, issued January 4, 1955; or emulsions of the mixed-grain type, such as described in Carroll and Hanson U.S. Patent 2,592,243, issued April 8, 1952. These agents can also be used in emulsions which form latent images predominantly on the surface of the silver halide crystal or in emulsions which form latent images predominantly inside the silver halide crystal, such as 10 those described in Davey and Knott U.S. Patent 2,592,- 250, issued April 8, 1952.

These may also be used in emulsions intended for use in diifusion transfer processes which utilize the undeveloped silver halide in the nonim age areas of the negative to form a positive by dissolving the undeveloped silver halide and precipitating it on a receiving layer in close proximity to the original silver halide emulsion layer. Such processes are described in Rott U.S. Patent 2,352,- 014, issued June 20, 1944, and Land U.S. Patents 2,584,- 029, issued January 29, 1952; 2,698,236, issued December 28, 1954, and 2,543,181, issued February 27, 1951; and Yackel et al. U.S. patent application Serial No. 5 86,- 705, filed May 23, 1956. They may also be used in color transfer processes which utilize the diffusion transfer of an image-Wise distribution of developer, coupler or dye, from a light-sensitive layer to a second layer, while the two layers are in close proximity to one another. Color processes of this type are described in Land U.S. Patents 2,559,643, issued July 10, 1951, and 2,698,- 798, issued January 4, 1955; Land and Rogers Belgian Patents 554,933 and 554,934, granted August 12, 1957; International Polaroid Belgian Patents 554,212, granted July 16, 1957, and 554,935, granted August 12, 1957; Yutzy U.S. Patent 2,756,142, granted July 24, 1956, and Whitmore and Mader U.S. patent application Serial No. 734,141, filed May 9, 1958.

In the preparation of the silver halide dispersions employed for preparing silver halide emulsions, there may be employed as the dispersing agent for the silver halide in its preparation, gelatin or some other colloidal material such as colloidal albumin, a cellulose derivative, or a synthetic resin, for instance, a polyvinyl compound. Some colloids which may be used are polyvinyl alcohol or a hydrolyzed polyvinyl acetate as described in Lowe U.S. Patent 2,286,215, issued June 16, 1942; a far hydrolyzed cellulose ester such as cellulose acetate hydrolyzed to an acetyl content of 1926% as described in U.S. Patent 2,327,808 of Lowe and Clark, issued August 24, 1943; a water-soluble ethanolamine cellulose acetate as described in Yutzy U.S. Patent 2,322,085, issued June 15, 1943; a polyacrylamide having a combined acrylamide content of 30-60% and a specific viscosity of 0.25-1.5 or an imidized polyacrylarnide of like acrylamide content and viscosity as described in Lowe, Minsk and Kenyon U.S. Patent 2,541,474, issued February 13, 1951; zein as described in Lowe U.S. Patent 2,563,791, issued August 7, 1951; a vinyl alcohol polymer containing urethane carboxylic acid groups of the type described in Unruh and Smith U.S. Patent 2,768,154, issued October 23, 1956; or containing cyano-acetyl groups such as the vinyl alcohol-vinyl cyanoacetate copolyrner as described in Unruh, Smith and Priest U.S. Patent 2,808,331, issued October 1, 1957; or a polymeric material which Y results from polymerizing a protein or a saturated acylated protein with a monomer having a vinyl group as described in U.S. Patent 2,852,382, of Illingsworth, Dann and Gates, issued September 16, 1958.

if desired, compatible mixtures of two or more of these colloids may be employed for dispersing the silver halide in its preparation. Combinations of these antifoggants, sensit-izers, hardeners, etc, vmay be used.

The sensitizing compounds of our invention can be used both in emulsions intended for black-and-white photogr raphy, or emulsions intended for color photography.

When used for this latter purpose, they can be used in emulsions containing color-forming compounds or coupiers, or they can be used in emulsions which are to be color-developed in developers containing the colorforming compounds or couplers. In either type of color photography, the particular color-forming compounds or couplers react with the oxidation products of color developers (particularly phenylenediamine developers) to provide subtractively-colored images. The color-forming compounds can be of the customary types employed in 1 3 l-p-laurylphenyl-3-methyl-5-pyrazolone 1-fi-naphthyl-3amyl-5-pyrazolone l-p-nitrophenyl-3-n-amyl-5-pyrazolone l-p-pl1enoxyphenyl-3-n-amyl-5-pyrazolone 1-pheny-l-3-n-amyl-5-pyrazolone 1,4-phenylene bis-3-( l-phenyl-S-pyrazolone) l-phenyl-3-acetylamino-5-pyrazolone l-phenyl-3-propionylamino-S-pyrazolone 1phenyl-3-n-valerylamino-5-pyrazolone l-phenyl-3-chloroacetylamino-5-pyrazolone 1-phenyl-B-dichloroacetylamino-S-pyrazolone 1-phenyl-3-benzoylamino-5-pyrazolone l-phenyl-3- (m-aminobenzoyl) amino-pyra2olone l-p-henyl-3-(p-sec. amylbenzoylamino) -5-pyrazolone l-phenyl-3-diamylbenzoylamino-S-wrazolone 1-pheny1-3-B-naphthoylamino-S-pyrazolone lpheny-l-3-phenylcarbamylamino-S-pyrazolone 1-phenyl-3-palmity]amino-S-pyrazolone 1-phenyl-3-benzenesulfonylamino-S-pyrazolone l- (p-phenoxyphenyl) -3 (p-tert. amyloxybenzoyl) amino- S-pyrazolone 1- 2,4',6'-tribromophenyl) -3-benzamido-5-pyrazolone l- 2,4,6'-trichlorophenyl) -3-benzamido-5-pyrazolone l- 2,4,6-trichlorophenyl) -3-phenylacetamido-5- pyrazolone 1-(2',4,6-tribromophenyl)-3-phenylacetamido-5- pyrazolone l-(2,4'-dichlorophenyl) -3- [3- (2',4"-di-tert.

amylphenoxyacetamido benzamido] -5-pyrazolone 1-(2,4',6'-trichlorophenyl) -3-[3"-(2"',4"'-di-te1-t.

amylphenoxyacetamido) benzamido -5-pyrazolone l-(2',4',6-tribromophenyl -3-[3- (2,4"-di-tert.

amylphenoxyacetamido benzamido] -5-pyrazolone 1-(2',4',6-trichlorophenyl)-3- [B-(2',4"-di-tert. amylphenoxy)propionamido] -5-pyrazolone 1-( 2,4,6-tribromophenyl)-3- [fi-(2,4-di-tert. amylphenoxy propionamido -5 -pyrazol one 1-(2,5-dichloro) -3-[3"-(4-tert. amylphenoxy)- benzamido1-5-pyrazolone 1(2',4',6-tribromophenyl)-3-[3"-(4"-tert. amylphenoxy -benzamido] -5-pyrazolone l-( 2,5 -dichlorophenyl) -3-[3-(2"',4'-di-tert. amylphenoxyacet-amido)benzamido1-5-pyrazolone COUPLERS PRODUCING YELLOW IMAGES N-amyl-p -b enzoylacetaminobenzenes-ulfonate N- 4-anisoylacetaminobenzenesnlfonyl -N-benzylmtoluidine N- 4-benzoylacetaminobenzenesulfonyl) N-benzyl-mtoluidine N- 4-benzoylacetaminobenzenesulfonyl) -N-n-amyl-ptoluidine N- 4 benzoylacetaniinobenzenesulfonyl) -N-benzylaniline w- (p-Benzoylbenzoyl) acetanilide w-BenZOylaCet-Z,5-dichloroanilide w-Benzoyl'p-sec. amylacetanilide N,N-di w-benzoylacetyl) -p-phenylenediamine N,N-diacetoacetamino) diphenyl Ot-{ 3 e( 2,4-di-tert.-amylphenoxy) aeetamido] benzoyl}- Z-methoxyacetanilide 4,4'-diacetoacetamino -3,3 -dimethyldiphenyl p,p-Di-( acetoacetamino) diphenylmethane Ethyl-p-benzoylacetaminobenzenesulfonate Nonyl-p-benzoylacetaminobenzenesulfonate 1\ -phenyl-N- (p-acetoacetaminophenyl) urea n-Propyl-p-benzoylacetaminobenzenesulfonate acetoacetpiperidine w-Benzoylacetpiperidide N(w-benzoylacetyl) -1,2,3,4-tetrahydroquinoline N w-benzoylacety-l morpholine As can be seen by reference to the large number of into several portions.

sensi-tizers included within our invention, as Well as the large number of color-forming compounds which can be employed in combination therewith, a number of combinations of sensitizing compounds and color-forming compounds is possible. In order to determine quickly the effectiveness of a particular combination, it has been found that the screening technique described by Pontius and Thompson in Photo. Sci. Eng, vol. 1, pages 4-51, can be used to get an idea of the potential effectiveness of a given combination for use in a photographic color element containing a coupler. This technique does not necessitate the preparation of any coupler dispersions, but the sensitizers can be added to ordinary photographic silver halide emulsions of the type used in black-andwhite photography, such as gelatino-silver-bromiodide emulsions, and the emulsions exposed in an intensity scale sensitometer to daylight quality radiation for a fraction of a second (usually & and processed for about 15 minutes in a phenylenediamine color developer, to which has been added 10 g. per liter of H-acid. The pH of this developer is usually adjusted to 10.8 by adding sodium hydroxide. A suitable developer composition for this screening technique is as follows:

, Benzyl alcohol cc 10 Sodium hexamethaphosphate g 2.0 Sodium sulfite g 2.0 Sodium hydroxide g 3.4 H-acid (lamino-8-naphthol-3,6 disulfonic acid) 4-amino-3-rnethyl-N-ethyl-N-(,B methyl sulfonamidoethyl)aniline sulfate g 8.0 Sodium carbonate monohydrate g 40.0 Sodium bromide g 1.5 Sodium thiocyanate g 0.2 Benzotriazole g .03

Water total to 1 liter, pH 10.8 i .l.

The relative speed, gamma and fog for coatings processed in this manner are given in Table I below.

The following technique Was used to determine the effectiveness of our compounds as sensitizer-s in photographic silver halide emulsions designed for black-andwhite photography.

An ordinary photographic silver bromiodide emulsion containing a sensitizing dye, a sulfur sensitizer of the type mentioned in Sheppard US. Patent 1,623,499, mentioned above, and gold sensitized in the manner indicated in US. Patent 2,448,060, mentioned above, was divided sensitizing compounds obtained as described above and identified by the example numbers given above, were then added in solutions in an organic solvent, such as ethanol or N,N-dimethylformamide in the amounts indicated in Table I below. The various portions of emulsions were then coated on transparent supports, such as cellulose acetate, and then dried. The dried coatings were exposed for about sec. to daylight quality radiation in Eastman type Ib sensitometer. The coatings were then developed for about 5 minutes in a photographic developer having the following compositions.

DK-S0z G. N-methyl-p-aminophenol sulfate 2.5 Hy roquinone 2.5 Sodium sulfite (dry) 30.0 Sodium borate 10.0 Potassium bromide 0.5

Water to make one liter.

The relative speed, as compared with a portion of the same batch of emulsion containing no polyoxathioether sensitizer, gamma and fog for the coatings, were then measured. The results are given in the following table,

15 wherein the compound numbers correspond to the numbers of the above examples:

TABLE I DK-50 15 Color Developer g./mol. Compound Silver N o. Halide Rela- Gam- Rela- Gamtive ma Fog tive ma Fog Speed Speed The effect of our polyoxathioether sensitizers has been illustrated above with particular reference to ordinary photographic silver bromiodide emulsions, although it is to be understood that other silver halide emulsions can be employed to like advantage.

While the prior art has previously suggested adding various thioether compounds to photographic silver halide emulsions for the purpose of increasing sensitivity, this has usually been done in connection with compounds containing ionic substituents on both terminal positions. However, it has been found that the compounds useful in our invention have marked advantages over such types of ionic sensitizers. For example, while the product of Ex ample 1 above increased the speed of an ordinary photographic silver bromiodide emulsion by 38 percent at a concentration of 3.0 grams per mole of silver halide, the corresponding ionic compound, 1,14-bis pyridinium-6,9- dioXa-3,lZ-dithiatetradecane-di-p-toluenesulfonate, gave a speed increase of only 12 percent at the same concentration. When the diperchlorate salt was used in place of the ditoluenesulfonate salt, there was an actual speed loss of 35 percent.

It has also been found that while tetraethylene glycol is of no practical use in increasing the sensitivity of photographic silver halide emulsions, the compounds of our invention are quite useful in sensitizing photographic silver halide emulsions in the manner described.

The following data show the effect produced by adding a sensitizing compound of our invention to an ordinary negative speed silver bromiodide emulsion which has been digested to optimum sensitivity with a mixture of a labile sulfur compound of the type shown in US. Patent 1,623,499 and a gold compound of the type shown in US. Patent 2,448,060. The emulsion had been red-sensitized to that region of the spectrum lying between about 600 and 700 mg and it contained a coupler dispersion of one of the color-forming compounds for producing the cyan image upon color development, such as a dispersion of a phenol coupler, e.g., any one of couplers Nos. 1 to 6 of Fierke U.S. Patent 2,801,171 (column 2) in a suitable solvent, such as tri-o-cresylphosphate or dibutylphthalate. In aliquot samples of the same emulsions, there were incorporated polythiallkylenediol sensitizers as identified in the table. The emulsions were then coated on conventional film support and dried. The coatings were exposed in an Eastman type lb sensitometer for X Sec. to the light emitted by a 500-watt tungsten lamp adjusted to 6l00 K. and further modulated by a Wratten No. 15 filter. The exposed coatings were then processed through a reversal process, such as the following:

The exposed film was developed in a developer having the following compositions:

Sodium hexametaphosphate g 2.0 N-methyl-p-aminophenol sulfate g 6.0 Sodium sulfite, anhydrous g 50.0 Hydroquinone g 6.0 Sodium carbonate monohydrate g 35.0 Potassium bromide g 2.0 Sodium thiocyanate g 1.5

0.5% solution of o-nitrobenzimidazole nitrate cc 12.0 0.1% solution of potassium iodide cc- 10.0 Water to make 1 liter.

The element was then thoroughly washed with water and treated in a hardening bath having the following composition:

G. Potassium chrome alum crystals 30.0 Water to make 1 liter.

The element was then thoroughly washed with water and treated for 30 seconds in a solution having the following composition:

G. Sodium borohydride 0.25 Sodium hydroxide 4.0

Water to make 1 liter.

The element was then treated in a color developer having the following composition:

Water to make 1 liter.

4amino N ethy1-N-(B-methanesulfonamidoethyl)alt-toluidine sesquisulfate monohydrate.

The element was then thoroughly washed with water and treated in a clearing and fixing bath having the following composition:

G. Sodium thiosulfate 150.0 Sodium bisulfite 20.0

Water to make 1 liter.

The element was then treated in a bleach bath having the following composition:

G. Potassium dichromate 5.0 Potassium ferricyanide 70.0 Potassium bromide 20.0

Water to make 1 liter.

The element was again washed and treated once again with the clearing and fixing bath identified above. The element was again washed and treated in a stabilizing bath havingthe following composition:

Formaldehyde (37% by weight) cc 7.0 Dispersing agent 1 g 0.5 Water to make 1 liter.

1 Such as Triton X i.e., an alkylaryl polyether alcohol (oetylphenoxypolyethoxy ethanol).

The following photographic data were obtained:

TABLE II Coating Ooncen- Relative No. Description tr at-ion, Dmux. Speed g/ruole (a) Control Ref. 100 (b) 3,9,15-triXa-6,l2- .3 10 115 dithiahcptadecane. (c) do 2.0 0 115 a 2,8,11,17-tetroxa5,14- 3.0 0 120 dithiaoctadecane. 3,9,12,18-tvtr0Xa-6,15- 3. 0 44 219 dithiaeicosanc. 3,6,12,18,2l-pentoxa- .9 18 132 9,15-dithiatricosane. 0 3.0 .58 159 3,6,15,18-tetrOXt1 9J2- 03 06 126 dithiaeicosane. do .30 .08 209 1,20-dihydroXy-3,9,12, 03 0 120 l8-tetroxa-6,15-dithiaeicosane-4,17- dione. (k) do .30 .34 316 (Z) 1,17-Clihydroxy-3,9, .3 16 229 15-trioxa-6,12-dithiaheptadecane-l, 14-dione. (m) o .9 .60 282 (n) 1,23-dihydroxy-3,6,12, .l 32 115 l7,2l-pentoxa-9,ldithiatricosane-7, 17-dione. (o) do a 3 08 148 (p) 2,5,11,14,20,23-Hexoxa- .3 10 141 17-dithiatetracosaneBJQ-dione. (q) 2,5,11,17,20-Pent0xa- .3 .02 126 8,14-dithioheneic0sane-6,16-dione. (r) do 9 06 126 While the effect of our sensitizers has been illustrated in Table 11 above with respect to a photographic element having only one color-sensitized layer, it is to be understood that the advantages are also obtained in multilayer tfilms containing a plurality of photographic emulsion layers which have their sensitivity in different regions of the spectrum. The sensitizers are effective not only in redsensitized emulsions but in emulsions which have their maximum sensitivity in the blue region of the spectrum, or in emulsions which have their maximum sensitivity in the green region of the spectrum.

It has also been found that photographic silver halide emulsions can be sensitized by compounds similar to those of Formula 1 above, except that one or more of the ethylene groups is replaced by methylene, propylene, etc.

The invention has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention as described hereinabove and as defined in the appended claims.

What We claim as our invention and desire secured by Letters Patent of the United States is:

1. A photographic silver halide emulsion sensitized with a non-polymeric sensitizer selected from the class represented by the following general formula:

wherein R represents a member selected from the class consisting of a hydroxyl group, an alkoxyl group, and a carbamyl group, R represents an ethylene radical, X represents a divalent radical selected from the class consisting of an oxygen atom, a sulfur atom, and the group X CH CH X X and X each represents a divalent radical selected from the class consisting of an oxygen atom and a sulfur atom, provided one of the radicals selected from the class consisting of X, X and X is an oxygen atom and provided one of the radicals selected 18 from the class consisting of X, X and X is a sulfur atom, X, represents the divalent radical -CH2(]% O d represents a positive whole number of from 1 to 2 and n represents a positive whole number of from 1 to 3.

2. A photographic silver halide emulsion as defined in claim 1, said silver halide emulsion being additionally sensitized with a labile sulfur compound.

3. A photographic silver halide emulsion as defined in claim 1, said silver halide emulsion being additionally sensitized with a gold compound.

4. A photographic silver halide emulsion as defined in claim 1, said silver halide emulsion being additionally sensitized with a labile sulfur compound and a gold compound.

5. A photographic silver halide emulsion sensitized with a non-polymeric sensitizer selected from the class represented by the following general formula:

wherein R represents a member selected from the class consisting of a hydroxyl group, an alkoxyl group and a carbamyl group, X represents a divalent radical selected from the class consisting of an oxygen atom, a sulfur atom, and the radical -X CH CH X X and X each represents a divalent radical selected from the class consisting of an oxygen atom and a sulfur atom, provided one of the radicals selected from the class consisting of X, X and X represents an oxygen atom and provided one of the radicals selected from the class consisting of X, X and X represents a sulfur atom, and n represents a positive whole number of from 1 to 3.

6. A photographic silver halide emulsion as defined in claim 5 wherein the silver halide is silver bromiodide.

7. A photographic silver halide emulsion. sensitized with a non-polymeric sensitizer selected from the class represented by the following general formula:

wherein R represents a member selected from the class consisting of a hydroxyl group, an alkoxyl group, and a carbamyl group, R represents an ethylene radical, X represents a divalent radical selected from the class consisting of an oxygen atom, a sulfur atom and the radical X CH CH X X and X each represents a divalent radical selected fiom the class consisting of an oxygen atom and a sulfur atom, provided one of the radicals selected from the class consisting of X, X and X represents an oxygen atom and one of the radicals selected from the class consisting of X, X, and X represents a sulfur atom, and n represents a positive whole number of from 1 to 3.

8. A photographic silver halide emulsion as defined in claim 7 wherein the silver halide is silver bromiodide.

9. A photographic silver halide emulsion containing a sensitizing amount of the compound represented by the following formula:

HOCH CH SCH CH OCH CH OCH CH SCH CH OH 10. A photographic silver halide emulsion containing a sensitizing amount of the compound represented by the following formula:

CH CH OCH CH SCH CH OCH CH OCH CH SCH CH OCH CH 11. A photographic silver halide emulsion containing a sensitizing amount of the compound represented by the following formula:

nocn cn ooccn scn cn ocn cn scn coocn cn on 12. A photographic silver halide emulsion containing V 19 a sensitizing amount of the compound represented by the following formula:

HOCH CH OCH CH OOCCH SCH CH OCH CH SCH COOCH CH OCH CH OH 13. A photographic silver halide emulsion containing a sensitizing amount of the compound represented by the following formula:

HOCH CH OOCCH SCH CH OCH CH OCH CH SCH COOCH CH OH 14. A photographic silver halide emulsion containing a color-forming compound capable of coupling with the oxidation products of a color developer containing at least one primary aminoaryl group to produce a colored compound, said emulsion containing a sensitizing amount of a compound selected from those represented by the following general formula:

wherein R represents a member selected from the class consisting of a hydroxyl group, an alkoxyl group, and a carbamyl group, R represents an ethylene radical, X represents a divalent radical selected from the class consisting of an oxygen atom, a sulfur atom, and the group --X CH CH X X and X each represents a divalent radical selected from the class consisting of an oxygen atom and a sulfur atom, provided one of the radicals selected from the class consisting of X, X and X is an oxygen atom and provided one of the radicals selected from the class consisting of X, X and X is a sulfur atom, X, represents the divalent radical d represents a positive Whole number of from 1 to 2 and n represents a positive whole number of from 1 to 3.

15. A photographic silver halide emulsion containing a color-forming compound capable of coupling with the oxidation products of a color developer containing at least one primary aminoaryl group to produce a colored compound, said emulsion containing a sensitizing amount of a compound selected from those represented by the following general formula:

wherein R represents a member selected from the class consisting of a hydroxyl group, an alkoxyl group, and a carbamyl group, R represents an ethylene radical, X represents a divalent radical selected from the class consisting of an oxygen atom, a sulfur atom and the radical --X CH CH X X and X each represents a divalent radical selected from the class consisting of an oxygen atom and a sulfur atom, provided one of the radicals selected from the class consisting of X, X and X represents an oxygen atom and one of the radicals selected from the class consisting of X, X and X represents a sulfur atom, and n represents a positive whole number of from 1 to 3.

16. A photographic silver halide emulsion containing a color-forming compound capable of coupling with the oxidation products of a color developer containing at least one primary aminoaryl group to produce a colored compound, said emulsion containing a sensitizing amount of a compound selected from those represented by the following general formula:

wherein R represents a member selected from the class consisting of a hydroxyl group, an alkoxyl group and a carbamyl group, X represents a divalent radical selected from the class consisting of an oxygen atom, a sulfur atom, and the radical -X CH CH X X and X each represents a divalent radical selected from the class consisting of an oxygen atom and a sulfur atom, provided one of the radicals selected from the class consisting of X, X and X represents an oxygen atom and provided one of the radicals selected from the class consisting of X, X and X represents a sulfur atom, and n represents a positive whole number of from 1 to 3.

17. A photographic silver halide emulsion containing a color-forming compound capable of coupling with the oxidation products of a color developer containing at least one primary aminoaryl group to produce a colored compound, said emulsion containing a sensitizing amount of the compound represented by the following formula:

cn cn ocn cn scrncmocn cn oon,cn scn cn ocn cn 19. A photographic silver halide emulsion containing a color-forming compound capable of coupling with the oxidation products of a color developer containing at least one primary aminoaryl group to produce a colored compound, said emulsion containing a sensitizing amount of the compound represented by the following formula:

HOCH CH OOCCH SCH CH OCH CH SCH COOCH CH OH 20. A photographic silver halide emulsion containing a color-forming compound capable of coupling with the oxidation products of a color developer containing at least one primary aminoaryl group to produce a colored compound, said emulsion containing a sensitizing amount of the compound represented by the following formula:

HOCH CH OCH CH OOCCH SCH CH OCH CH SCH COOCH CH OCH CH OH 21. A photographic silver halide emulsion containing a color-forming compound capable of coupling with the oxidation products of a color developer containing at least one primary aminoaryl group to produce a colored compound, said emulsion containing a sensitizing amount of the compound represented by the following formula:

HOCH CH OOCCH SCI-I CH OCH CH OCH CH SCH COOCH CH OH References Cited in the file of this patent UNITED STATES PATENTS Matthies Dec. 31, 1929 "Blake et al July 8, 1947 Blake May 11, 1948 

14. A PHOTOGRAPHIC SILVER HALIDE EMULSION CONTAINING A COLOR-FORMING COMPOUND CAPABLE OF COUPLING WITH THE OXIDATION PRODUCTS OF A COLOR DEVELOPING CONTAINING AT LEAST ONE PRIMARY ANIOARYL GEOUP TO PRODUCE A COLORED COMPOUND, SAID EMULSION CONTAINING A SENSITIZING AMOUNT OF A COMPOUND SELECTED FROM THOSE REPRESENTED BY THE FOLLOWING GENERAL FORMULA: 